How to make a flat roof with your own hands. Projects of houses with a flat roof Houses with a flat roof are called

For many people, the name “flat roof” is associated primarily with multi-story buildings. A flat roof - the pros and cons of which we will consider in this article - was practically not used in low-rise construction a dozen years ago. However, today creating such a roof in a country house is not a problem: modern materials and technologies make it possible to create a flat roof with appropriate consumer characteristics and at an affordable price.

A flat roof is significantly smaller in area than a pitched roof, which allows you to save on materials and construction work.
Thanks to the relatively smaller area of the flat roof, it is possible to optimize costs.
The construction of a flat roof is carried out easier and in a shorter time, compared to a pitched roof, since the necessary materials for installation are located right at the feet of the workers on a flat surface. The same can be said about the repair and maintenance of a flat roof - working on an almost horizontal roof is incomparably more comfortable than on a sloping one.
On a flat roof, installation and subsequent service work with all kinds of equipment (air conditioning systems, solar panels, antennas, etc.) is more convenient.
The use of a flat roof is an opportunity to obtain additional useful territory, which can be used as a place where you can relax in the fresh air, play sports, create a garden, flower garden, etc. Today, there are technologies that make it possible to cover the roof even with paving slabs or paving stones. A roof paved with beautiful tiles, combined with a green lawn, garden furniture, a gazebo and a fireplace, can become a place for a comfortable family holiday.

Houses with flat roofs are very popular now

A flat roof, in addition to its advantages, has a number of disadvantages:

As a result of heavy snowfalls, a lot of snow accumulates on flat roofs, which, when melted, often causes leaks.
Sometimes the use of internal drains is required.
There is a risk of the internal drain becoming clogged or freezing.
There is a need for mechanical cleaning of the roof from too large accumulations of snow.
Regular monitoring of the moisture content of the insulation and the tightness of the roof is necessary.

Types of flat roofs

There are four types of flat roofs:

Flat roof base

In accordance with building codes, a flat roof, the pros and cons of which we discussed above, must have a base in the form of reinforced concrete floor slabs or corrugated sheets.

Subtleties of waterproofing

The durability of the roofing structure and its resistance to various negative influences depends on the use of special mixtures and technological processes for the production of roofing materials. Depending on the roofing materials, they are usually divided into three categories:

Bitumen roofs, as well as polymer-bitumen based on roofing felt. These materials are available due to their low cost. Fused bitumen-polymer compositions are rolled waterproofing and roofing sheets based on synthetics, on both sides of which a special bitumen is used that retains elasticity even at extremely low temperatures (down to -50 degrees Celsius). During the installation of waterproofing, carried out using gas burners, the rolls are fused together. Roof waterproofing can also be carried out with self-adhesive materials based on polymers and bitumen. In this case, the mastic is applied to the bottom surface of the roll and, when treated with a solvent, acquires the properties of glue. The disadvantage of bitumen roofing is its fragility.
Membrane roofs with a base made of foil, rubber or polymers. This material has solid strength and is resistant to fire and other negative environmental influences. The membranes are glued to the screed or simply lie on the base, being loaded with ballast, or are attached mechanically or using glue. To connect the membrane sheets, special welding machines are used that hold the material together with hot air.
Roofs based on liquid polymers, which after cooling do not form seams. Such materials are especially often used for structures with complex geometries.

It is very important to properly waterproof your flat roof.

Whatever material is chosen, the joints between the rolls and the junctions with various roof elements must be waterproof. One of the main components of a successful waterproofing device is a high-quality sealant. During the period of operation, the roof is subject to negative influences of the external environment (moisture, hail, stones, strong temperature changes, etc.). Therefore, a high-quality sealant must be resistant to mechanical and temperature influences.

Mastic is usually used as a sealant - putty, which is based on elastic polyurethane resins. After application to the roof, the mastic polymerizes, resulting in the formation of a continuous rubber-like membrane that has waterproofing properties and protects the roofing from mechanical damage.

Mastic is ideal for flat roofing, it is safe, has high adhesion to building surfaces, and is highly resistant to ultraviolet radiation, precipitation and all kinds of microorganisms. It is applied with a brush, roller or airless spray - in two multi-colored layers, which allows you to control the quality, layer thickness and uniformity of distribution of the sealant.

How to arrange water drainage

Regardless of the materials used, a flat roof must have a certain slope to drain water (usually within 3-5%) that appears on the roof as a result of precipitation. The drainage system should be thought out at the building design stage. Gutters determine how effectively moisture will be removed from the roof surface. To prevent gutters from freezing in winter, they are equipped with special thermal cables.

Drains can be organized, when both external and internal water supply is created, and unorganized. When creating an internal water supply system, the roof surface is divided into approximately equal parts of 150-200 square meters each. In places with a slope, drainage funnels are installed, equipped with baskets for catching debris. Typically, funnels are located in the center of the roof, and the pipes are located inside the building.

Rules for insulation and vapor barrier of a flat roof

A flat roof needs insulation. In the absence of a layer of thermal insulation, condensation forms on the roof surface as a result of the contact of warm air masses and the cold surface of the roof. Condensation appears as water stains on the ceilings of the house, and the roof structure gradually collapses.

The roof design involves a base on which a layer of vapor barrier material is laid. The function of a vapor barrier is to protect the insulation from diffuse moisture coming from the premises of the building. The vapor barrier layer includes a glass fiber reinforced membrane (based on bitumen and polymers) or a vapor barrier film. The layer is laid on top of the screed, and along the edges of the roofing structure it is placed vertically to a height exceeding the height of the insulating material. The seams are sealed.

Insulation is placed above the vapor barrier layer, and a bitumen-based waterproofing carpet is placed on top of it. If expanded clay is used as insulation, then it is necessary to make a cement screed over it, then laying a couple of layers of waterproofing. If the roof is planned to be light (in the case where significant loads are not expected on it), then the waterproofing is simply glued along the entire perimeter of the roof.

For roofs without attics, both external and internal insulation methods are used. The external method is used more often, as its execution is simpler. There are two options for thermal insulation: double-layer and single-layer. The decision about which option to use in practice depends on heat engineering calculations and roof strength requirements. Thermal insulation slabs are placed on the roof structure based on the principle of “staggered seams”. With a two-layer coating of thermal insulation, the joints of the lower and upper slabs are also separated. In the area where the slabs adjoin the parapet, lanterns and walls, thermal insulating edges are created. Thermal insulation materials are attached to the base mechanically (screws, dowels), ballast (pebbles, paving slabs) or glue.

Features of roof ventilation

The roof structure must be equipped with a ventilation system. As a result of a violation of the tightness of the vapor barrier layer, moisture enters the insulating layer. A thick layer of waterproofing prevents evaporation from occurring, and moisture accumulates in the insulation. As a result, the material loses its insulation characteristics, and moisture appears on the ceilings of the building in the form of stains. In addition, water causes the waterproofing to swell, and at low temperatures, freezing water tears the waterproofing material away from the base. Temperature changes and mechanical damage contribute to the formation of cracks in the roof, which results in roof leaks.

To avoid these problems, the roof must “breathe”. For this, aerators are used - special devices in the form of plastic or metal pipes. They are covered with umbrella caps and are evenly distributed throughout the entire roof area, gravitating towards its highest points. The aeration mechanism works based on the principle of different pressures, which are created by air flows, removing excess moisture vapor from under the roof and preventing water bubbles from forming.

The installation of a roof is a responsible technological operation. Any, even minor, mistake in the design or construction of a roof can cause it to leak in the future. Therefore, when creating a roof, you need to pay special attention to the correct selection of hydro- and thermal insulation materials, accurately calculate the upcoming loads on the roof structure, and also select a team of competent builders.

The construction of a gable or hip roof is not always rational and practical when it comes to outbuildings, industrial and commercial facilities, and sometimes private houses in a modern style. The high consumption of material and the complex rafter system make the construction of these structures an economically unprofitable and protracted undertaking. While flat roofing projects significantly reduce construction costs, are quick to build and suitable for almost any structure.

A house with a flat roof is reliably protected from increased wind loads. However, without slopes, it cannot quickly drain rain and melt water from the roof surface.

The situation is complicated by the fact that the surface of roofing materials has a rough structure, which does not allow moisture and snow to slide off freely. Therefore, the installation of a do-it-yourself flat roof must meet the strict requirements of building codes for waterproofing, slope and construction technology.

The structure of the roofing pie

The need for a high level of protection from moisture forces the roofing materials of a flat roof to be placed in layers, one above the other, forming a so-called “pie”. If you look at its cross-sectional structure, you can see the following layers:

Flat base made of concrete slabs or profiled metal sheets. It provides rigidity to the structure, bears the weight of the roofing pie, transferring it to the load-bearing partitions and, ultimately, to the foundation. The base of the roof in use must be as rigid as possible.
Vapor barrier. A layer that is necessary to protect a flat roof from the penetration of vapors from internal heated rooms into the thickness of the insulation. When water settles on the thermal insulation in the form of condensation, it irreversibly reduces its insulation properties by more than half. The simplest vapor barrier is polyethylene film or bitumen-based coatings.
Insulation. For thermal insulation of a flat roof, backfill materials are used, such as expanded clay, perlite, slag, rolled materials, for example, mineral wool, and in the form of slabs, in particular polystyrene foam. By the way, insulation is used not only to regulate the temperature, but also to tilt a house with a flat roof. The main requirements for insulation are low hygroscopicity and thermal conductivity, light weight.
Waterproofing. A flat roof allows the use of roll materials for covering to protect against moisture: bitumen, polymer and bitumen-polymer. In addition to high waterproofing qualities, they must have resistance to temperature changes, elasticity, and a long service life.

Types of roofing and nuances of their installation

The construction of a flat roof is determined by the design and nature of its use. Some types that require a special approach during construction include the following:

Roof installation for unheated buildings

If a flat roof is being built with your own hands for an unheated utility room, for example, a barn, gazebo, shed or outbuilding, the slope is organized using support beams.

They are installed at an angle of 3 degrees, which is 30 mm for each linear meter of beam length. Then a base of unedged boards is laid on the beams, secured with nails or self-tapping screws.

Roofing felt, the most affordable material, is used as a waterproofing agent. It is produced and sold in roll form. The waterproofing is cut by cutting strips so as to lay them in the direction of the slope of the flat roof.

Strips of roofing felt are laid in stages with an overlap of 10-15 cm and fixed with wooden slats or steel strips every 60-70 cm in the direction of the drain, so as not to block the path of flowing moisture. A flat roof of an unheated room can be easily installed with your own hands, even by one worker without the help of helpers.

Roof installation for heated structures

If they are building a private house with a flat roof, which they plan to connect to a heating system, then the work takes place in the following order:

To build a house with a flat roof, the length of which exceeds 6 m, a beam with a cross-section of 150x150 mm or more, or a steel I-beam, is used to make support beams.

Monolithic concrete roofing

Another option for building a flat roof with your own hands is to use monolithic concrete. The process looks like this:

Leaning process

– arrangement of a small angle of the roof surface to organize drainage. Before building a house with a flat roof, it is better to decide in advance which drain you will install, internal or external, and make a drawing.

If provided, water should flow into water collection funnels using a slope, which are located 1 per 25 sq.m or more often. If you make an external drain, then moisture should enter the gutter. The slope is formed using the following methods:

A flat roof without proper slope is an unreliable shield between you and bad weather. Moisture that has no outlet will accumulate on the roof surface, causing roof destruction and leaks.

Video instruction

If previously flat roofs were made only on urban multi-storey buildings and were associated with constant leaks, today the situation has changed radically. These structures are used not only during the construction of multi-storey buildings, but also in the construction of prestigious private houses according to exclusive projects. Such changes became possible thanks to the emergence of completely new building materials and technologies.

Flat roofs are one of many types of roofing, and have both positive and negative sides. The advantages of such roofs include the following characteristics.

Saving building materials and speed of construction. The effect is achieved through physical savings - the area of a flat roof is much smaller than a gable roof. In addition, for this design there is no need to manufacture a complex rafter system with various purlins, supports, crossbars, mauerlats, etc. A small number of roof elements makes it possible to construct flat roofs independently without the involvement of expensive professional specialists.
True, for this you should have basic skills in performing roofing work and understand modern technologies and materials. Otherwise, attempts to reduce the estimated cost of the structure may result in large additional costs for unplanned repairs. And not only the roof itself, but also the interior of the buildings.
Possibility to use the roof as an exploitable one. On flat roofs you can build winter gardens, recreation areas, flower beds, small sports areas, etc. But in these cases, the roofs have a very complex structure and require a professional approach to all construction work.
Flat roofs make installation and periodic maintenance easier various engineering equipment: air conditioning and ventilation systems, solar panels, antennas, etc.

Unfortunately, such architectural structures also have disadvantages.

We have listed the real advantages and disadvantages; each developer should carefully analyze them before making a final decision.

Types of flat roofs in private houses

Thanks to new materials and technologies, designers have been able to create several types of flat roofs with unique performance characteristics.

Flat roof type	Brief description of technical and operational characteristics
	The most commonly used, simplest and cheapest type of roof. It is most often found on commercial buildings; it is rarely installed on private houses.
	A very prestigious roof allows you to use the area to increase the comfort of living in the building. The construction of such roofs requires high-quality materials and special technologies. The roof in use is often inverted.
	It differs from the usual one in the arrangement of layers of the roofing cake. Waterproofing is done directly on the supporting base; this feature protects the coating from mechanical damage. Geotextiles, extruded polystyrene foam, another layer of geotextiles and a ballast layer are laid on top of the waterproofing. Geotextiles allow water to flow to the drainage system, and ballast prevents layers from being undermined by strong gusts of wind.

Important. The cost of flat roofs varies widely; some options can be several times more expensive than gable roofs.

Roofing pie device

All flat roofs in residential buildings must be insulated; the structures consist of several layers. Each of them performs its own function and is critical for the roof.

Base

Can be reinforced concrete or wood.

Professional builders prefer reinforced concrete slabs, but not all houses can use them. The slabs are mounted only on brick or concrete facade walls; such elements are not used for wooden or frame buildings.

Vapor barrier

Prices for vapor barrier materials

Vapor barrier material

It is used only in two cases: the base of a flat roof is wooden and mineral wool is used as insulation.

But such options are rare; most often the base is made of a concrete slab, and durable extruded polystyrene is used for insulation. Both of these materials are not only resistant to steam, but also do not react to direct contact with water. Accordingly, when constructing roofs made of such materials, vapor protection is not required.

Insulation

There are two types of insulation that can be used in the construction of flat roofs.

Insulation can be installed in two ways.

Currently, architects in most cases prefer the second option for insulating a flat roof, keep this in mind. But practitioners advise installing insulation from inside the premises. Each developer must make his own decision.

Prices for thermal insulation materials

Thermal insulation materials

Practical recommendations for arranging a flat roof on a frame house

For example, we will take the option of arranging a flat roof on a wooden frame house. These buildings are very popular among many developers; they are quickly assembled, are relatively inexpensive and provide residents with a modern level of comfort.

How to make floors

For the ceiling you need to use I-beams; ordinary ones are not suitable due to very high loads. If the linear dimensions of ordinary beams are significantly increased, then their own weight will play a noticeable role in the calculations of the acting forces, and this is extremely undesirable for all structural loaded elements.

Important. If the house is large, then it is much more profitable to order short beams and splice them on site. This method simplifies the process of transporting and installing structures. When installing ceiling beams, you need to make a slight slope to allow water to drain away.

Video - Wooden floor

What to make waterproofing from

Prices for PVC membranes for roofing

PVC membrane for roofing

For sealing, it is recommended to use a modern high-quality membrane that is protected from the harmful effects of ultraviolet rays. The membrane thickness is at least 1.5 mm, the service life of such coatings is more than thirty years. Membranes must retain their original properties at temperatures of -30° and below. It must be borne in mind that situations may arise when in winter it is necessary to remove snow from the roof; the waterproofing must withstand mechanical forces and not be damaged.

How to install a funnel for receiving water

The diameter of the funnel must correspond to the roof area and the maximum water flow. The data is available in comparative tables and is attached to the instructions for using the elements. If for some reason there is no such instruction, then you need to consult with the seller.

The funnel is installed at the lowest point of the roof. The roof plane is divided into several sectors and each has a slight slope towards the drain. To prevent ice from accumulating in the funnel in winter, it is recommended to connect an electric heating system. Heating functions temporarily and only during the period when the temperature changes from positive to negative several times a day.

How to properly lay a waterproof membrane

The joints are boiled with a construction hairdryer and additionally filled with a special two-component glue. You should start from the very bottom edge, the width of the overlaps is at least 10 cm. To increase the strength of the fastening, each strip of the membrane is separately fixed with special fasteners, and the wide washers are then closed.

Along the perimeter of the parapet, the membrane is also screwed with washers of large diameter, the distance between them is approximately 20–30 cm.

How to drain water from a roof

Experienced builders do not recommend attempting to install external gutters and pipes on flat roofs to drain water to the ground. The best option is to run plastic pipes through the interior. Installation of the system should be done immediately after assembling the frame of the house; the pipes are hidden during the cladding of the internal walls. Due to this installation location, the possibility of freezing is completely eliminated, and the reliability of the system is significantly increased.

The best way to process OSB boards

There are many options, efficiency depends not only on the materials used, but also on the professionalism of the master. But practice shows that, all things being equal, bitumen mastics have the greatest reliability. Surfaces must be coated at least twice, this guarantees the tightness of the coating for a long period of time. Of course, the top membrane must also be of high quality and correctly installed.

A flat roof in a private house provides many different possibilities. With such a simple design, you can save on roofing materials and labor, and installation is carried out in a shorter time. It is also easier to place various systems on its surface: antennas, hoods, solar panels and others. In addition to all this, additional space can be used by arranging a garden, recreation area or greenhouse on it.

However, despite the cheaper installation, many nuances must be taken into account so that such a roof does not become a “headache” for the home owner.

Flat roof design

A flat roof, like any other, must fully perform all its functions: protection from water and its drainage and thermal insulation. In addition, it must have sufficient strength to withstand external loads.

This is what determines the structure of the roofing pie, which consists of the following mandatory elements.

Base. This part bears all the main loads. The ceiling must be very durable, but it all depends on whether the roof will be used or not. Most often, the base is a reinforced concrete slab laid on load-bearing walls, less often on non-residential buildings - a layer of profiled sheets.
Vapor barrier layer. Performs a protective function, which consists in preserving materials from steam penetrating from inside the room.
Thermal insulation. Reduces heat consumption from the house.
Waterproofing. A flat roof does not drain away all the water completely, like gable roofs; as a result, high-quality protection is needed from the penetration of room moisture.

For normal moisture removal, a slope is used. Most often, this is a screed that forms angles of inclination along which water can flow into a prepared system of trays for its removal from the roof plane.

Saving on any parts of a flat roof is unacceptable, otherwise it will lead to leaks, freezing and other negative phenomena of a poorly installed roof pie.

Types of Flat Roofs

The presence, order and sequence of individual elements of the roofing pie determine the type of roof. The following types of flat floor structures are distinguished:

Unexploited. These structures can be seen on multi-story buildings. It is believed that their surface is not intended for use and is designed for short-term stay of people. In this option, on non-residential buildings you can use a profiled sheet as a base.
Exploited. In this case, it is necessary to have a concrete base capable of withstanding heavy loads. The surfaces can be used as a garden, recreation area or even car parking. In addition to a solid base, it is important to observe the angle of inclination, which should not exceed 3 degrees.

Inversion. The design involves changing the order of layers of the cake. The waterproofing is placed under the insulation, which allows it to be protected from damage. Quite often this type of roofing is used in the construction of private residential buildings.
Ventilated. These types of roofing have a ventilation system (built-in aerators) that evaporate excess moisture from the thickness of the roofing cake. Can be combined with other types of roofs.

In addition, the type of roof depends on other factors, for example, whether the room is heated or not.

Installation of a flat roof on different types of buildings

Depending on whether the room will have a heating system or not, the technology for assembling the roof may differ during installation.

Roofs on unheated premises

Typically, unheated buildings are garages, sheds, gazebos, and various pavilions.

The required slope of 3 degrees on such buildings is formed by the load-bearing roof beams. The height difference is about 30 millimeters per 1 meter of beam length.
After laying the beams, a flooring is made that will serve as a base. These can be boards or profiled sheets. They are secured with self-tapping screws or other suitable fasteners.
If the room is unheated, you may miss a layer such as thermal insulation. Waterproofing material is laid on the base. Roofing felt is used as a waterproof coating. It is spread in overlapping strips (about 150 mm) and additionally fixed with slats, which are placed along the slope of the roof.

This is the simplest version of a flat roof, which can be mounted on a utility unheated room with your own hands at a minimal cost of money and time.

Assembling a flat roof on heated buildings

In residential buildings with a heating system, the roofing pie of a flat roof will be different. Here you will definitely need a thermal insulation layer, high-quality hydro- and vapor barrier. The presence of the latter is no less important, since water vapor can gradually ruin the entire roofing pie.

The floor under the base is assembled from wooden beams, which are placed at intervals of 900-1000 mm.
They are covered with flooring made of boards with a cross-section of 40-50 millimeters. The thickness of the lumber is selected depending on the distance between the beams. The larger it is, the thicker the boards are needed.
Roofing felt is laid on the flooring, it is cut and straightened in advance. Waterproofing sheets are laid with an overlap of about 100-150 mm.
The thermal insulation layer can be made using the bulk method. To do this, fill the resulting base with a layer of expanded clay up to 300 mm and level it.
Next, a cement-sand screed (minimum 30 mm thick) is poured onto the layer of thermal insulation backfill.
After the cement has hardened, the surface is covered with bitumen-based soil and covered with a layer of roofing felt.

You can also install a more solid roof made of monolithic concrete.

Monolithic concrete flat roof

In this option, you make a durable concrete base with your own hands.

An I-beam is used as support beams, which are laid level without forming a slope.
For pouring, you will need to prepare concrete of a grade not lower than M250; it is prepared in a concrete mixer, maintaining a ratio of 4:1.5:1:1, where the ingredients are crushed stone (20-25mm), cement (m400), water and sand, respectively.
For pouring, a base is made of boards, which are mounted on the lower flanges of I-beams and covered with roofing felt.
Fine crushed stone is poured on top of the waterproofing, which is filled with the resulting concrete. The filling must be done at one time, otherwise the structure of the roof will not be the same.
Next, expanded clay is poured in and a slope is made.

Leaning

Sloping is the formation of slight slopes on the surface of a flat roof, which allows water to be removed from its surface. The drainage system is assembled in two versions: external and internal. That is, the trays can be attached to the end of the roof or on its surface.

If the drainage gutters are located internally, the presence of drainage basins is planned in advance, the number of which is calculated as follows - 1 funnel per 25 square meters of roof area.

The slope can be formed in the following ways.

When filling expanded clay, plan the required slope. After which the bulk material is filled with a cement screed.
If a heat insulator is used in the form of cotton wool or polystyrene foam, its sheets are positioned so that they form the required slope of the plane.
For a monolithic concrete roof, pouring is carried out in such a way as to form the required slope of 3 degrees.

The entire unbending process should be planned in advance and a preliminary drawing diagram should be made. If you do not maintain the required slope, the accumulated water will gradually ruin the entire roofing pie, negating its protective function.